There is known a vehicle provided with a control device for controlling a drive system including a power distributing mechanism arranged to distribute an output of an engine to a first electric motor and an output shaft, and a second electric motor disposed between the output shaft of the power distributing mechanism and drive wheels of the vehicle. Examples of this control device include a control device for a hybrid vehicle as disclosed in Patent Document 1. In the hybrid vehicle drive systems disclosed in this document, a major portion of the drive force generated by the engine is mechanically transmitted directly to the drive wheels, while the rest of the drive force is electrically transmitted from the first electric motor to the second electric motor through an electric path therebetween, and the drive systems are controlled such that the engine is kept in an optimum operating state, permitting the vehicle to run with an improved fuel economy.    Patent Document 1: JP-2003-130202A    Patent Document 2: JP-2003-130203A    Patent Document 3: JP-2003-127681A    Patent Document 4: JP-11-19868A    Patent Document 5: JP-11-198670A    Patent Document 6: JP-11-217025A    Patent Document 7: WO 03/016749A1